The present invention generally relates to acoustics and more particularly to underwater sound transmitting or receiving systems with the unique property of having a directional constant beamwidth diffraction pattern over a wide band of frequencies either with or without scanning.
A prior invention, Robert L. Sternberg, U.S. patent application Ser. No. 784,186 recites a frequency independet FLYEYE type lens/filter arrangement. The device places its lens between its filter plate and sensor/transmitter. When used as a receiver the plane waves from a source on passing through the filter plate assume a conical shape that present problems to the focusing lens and result in distortion.